Spark-plug.



jw I x A. SCHMIDT.

SPARK PLUG- APPLICATION FILED AUG-3| 1912.

, 1,1 17,8 1'8. Patented July 27, 1915.

7fz'1naues v v I I 0 ml uberescz zdt I UNITED STATES PATENT OFFICE.

I ALBERT SCHMIDT, 0F FLINT, MICHIGAN, ASSIGNOR TO CHAMPION IGNITION COM-PANY, OF FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

SPARK-PLUG.

I Application filed August 3, 1912.

T 0 all whom it may concern Be it known that I, ALBERT SCHMIDT, acitizen of the Republic of France, residing at Flint, in the county ofGenesee and State of Michigan, have invented certain new and usefulImprovements in Spark-Plugs, of which the following is a specification,reference being had therein to the accompanying drawings.

The invention relates to spark plugs and has particular reference to thepacking means for preventing leakage between the insulator and themetallic case. In the present state of the art, it is usual to place acompressible annular gasket or packing between the opposed shouldersformed upon the porcelain insulator and the metallic case and tocompress this packing by a suitable gland. It is, however, necessary toadjust the gland to tighten the packing, and this adjustment oftenresults in a movement of the packing in relation to the surface of theinsulator. This insulator surface is more or less irregular andconsequently when the packing is removed from the position in which itis fitted it will not perfectly conform to the surface and the plug willtherefore leak. I have provided means for retaining the gasket in fixedrelation to the porcelain surface, so that adjustment of the plug willnot disturb this relation and cause leakage. In the drawings: Figure 1is a central longitudinal section through the spark plug. Fig. 2 is anenlarged section of the packing means. I

A is the outer metallic case; B the insulator; and C and D opposedshoulders formed upon the insulator and case. Between thes'eopposedshoulders is placed my improved packing comprising a compressible gasketE in contact with the shoulder C of the porcelain, and a metallic ringor washer F between said gasket and the shoulder D. The gasket E is of asufliciently yieldable nature to conform to the exact surface of theporcelain, compensating for any irregularities therein. The ring orwasher F has a true surface substantially I parallel with the surface ofthe porcelain and forming a firm backing for the gasket. The jointbetween the ring or washer F and the casin A is formed by a knife-edgebearing on the one engaging a surface on the other, this knife-edge Gbeing preferably Specification of Letters Patent.

With my improved construction Patented July 2'7, 1915.

Serial No. 713,053.

formed on the member A. The location of the knife-edge bearing is nearerthe axis of the porcelain than the mean diameter of the gasket E, withthe result that the friction between the gasket and the porcelain isgreater than the friction between the ring or collar F and theknife-edge bearing G. Thus ifthere is any rotative adjustment of theporcelain with respect to the case A this will not disturb the relationbetween the gasket E and the shoulder C, but will merely effect arotative adjustment of the collar F on the knife-edge bearing G, and asthe latter is a true surface such adjustment will not cause any leakage.Therefore the plug remains gas-tight.

What I claim as my invention is:

'1. In a spark plug, the combination with the outer case and theinsulator therein, having opposed annular shoulders, of a compressiblegasket between said shoulders engaging the shoulder on the insulator,and a solid ring between the gasket and the shoulder on said case,forming a backing for the gasket, said ring having an annular engagementwith the shoulder of the case, and the annular engaging portions of thering and the case shoulder having a less diameter than the mean diameterof the gasket surface bearing against the shoulder of the insulator.

2. In a spark plug, the combination with an outer case and an insulatortherein, having opposed shoulders, of a compressible gasket adjacent andconforming to the shoulder on said insulator, a metallic ring formingthe backing for said gasket, and an annular knife-edge bearing betweensaid metallic ring and shoulder on the case, having a less diameter thanthe mean diameter of the gasket surface bearing against the insulator.

3. In a spark plug, the combination with the outer metallic case and theinsulator therein, having opposed shoulders, of a compre'ssible gasketbetween said shoulders adjacent and conforming to the shoulder of theporcelain, a metallic ring or backing for said gasket confined whollywithin the space between said gasket and shoulder of the outer metalliccase, and aknife-ed e bear ing between said metallic ring or backing andthe shoulder of said case.

4:. In a spark plug, the combination with the outer case and theinsulator therein,

having opposed shoulders, of a 'yieldable' gasket engaging andconforming to the shoulder on saidinsulator, a solid metallic ringhaving a true surface substantially parallel with the shoulder on saidinsulator, said ring being adjacent to said gasket, and a knife-edgebearing between said ring and the shoulder on said outer case.

5. In a spark plug, the combination with the outer metallic case and theinsulator therein,v havingv opposed shoulders, of a yieldable gasketbetween said shoulders ad- In testimony whereof I aflix my signature inpresence of two Witnesses.

' ALBERT SCHMIDT.

Witnesses:

MAGIBEL BRIGKER,

F. J. UTLEY.,

